Chapter 5/6/7 MC Questions

A population has a mean of 80 and a standard deviation of 7. A sample of 49 observations will be taken. The probability that the sample mean will be larger than 82 is: A) 0.0228 B) 0.4772 C) 0.5228 D) 0.9772

A

A sample of 24 observations is taken from a population that has 150 elements. The sampling distribution of is: A) normal if the population is normally distributed. B) approximately normal because of the central limit theorem. C) approximately normal because the sample size is large in comparison to the population size. D) approximately normal because is always approximately normally distributed.

A

A value of 0.5 that is added to and/or subtracted from a value of x when the continuous normal distribution is used to approximate the discrete binomial distribution is called: A) continuity correction factor. B) continuity approximation factor. C) factor of conversion. D) probability density factor.

A

Convenience sampling is an example of: A) nonprobabilistic sampling. B) stratified sampling. C) cluster sampling. D) probabilistic sampling.

A

For a continuous random variable x, the height of the function at x is: A) named the probability density function f(x). B) the probability at a given value of x. C) a value less than zero. D) 0.50, since it is the middle value.

A

Which of the following is a characteristic of an experiment where the binomial probability distribution is applicable? A) Exactly two outcomes are possible on each trial B) The trials are dependent on each other C) The probabilities of the outcomes changes from one trial D) The experiment has at least two possible outcomes

A

A measure of the average value of a random variable is called a(n) A)coefficient of variation. B)expected value. C)variance. D)standard deviation.

B

A uniform probability distribution is a continuous probability distribution where the probability that the random variable assumes a value in any interval of equal length is: A) at least one B) the same for each interval. C) different for each interval. D) zero.

B

Four percent of the customers of a mortgage company default on their payments. A sample of five customers is selected. What is the probability that exactly two customers in the sample will default on their payments? A)0.7408 B)0.0142 C)0.9588 D)0.2592

B

From a group of 12 students, we want to select a random sample of 4 students to serve on a university committee. How many combination of random samples of 4 students can be selected? A) 20,736 B) 495 C) 16 D) 48

B

In a local university, 40% of the students live in the dormitories. A random sample of 80 students is selected for a particular study. The standard deviation of , known as the standard error of the proportion is approximately: A) 0.5477 B) 0.05477 C) 54.77 D) 5.477

B

Parameters are: A) numerical characteristics of either a sample or a population. B) numerical characteristics of a population. C) the averages taken from a sample. D) numerical characteristics of a sample.

B

A continuous random variable may assume: A) only the positive integer values in an interval. B)finite number of values in a collection of intervals C)any numerical value in an interval or collection of intervals. D)an infinite sequence of values.

C

As the sample size becomes larger, the sampling distribution of the sample mean approaches a: A) Chi-square distribution. B) Poisson distribution. C) Normal distribution. D) Binomial distribution.

C

For a continuous random variable x, the probability density function f(x) represents: A) the area under the curve at x. B) the probability at a given value of x. C) the height of the function at x. D) the area under the curve to the right of x.

C

For a normal distribution, a positive value of z indicates that: A) the area corresponding to the z is either positive or negative. B) the sample mean is smaller than the population mean. C) the sample mean is larger than the population mean. D) all the observations must have had positive values.

C

In a standard normal distribution, the: A)mean and the standard deviation are both 1. B)mean is 1 and the standard deviation is 0. C)mean is 0 and the standard deviation is 1. D)mean and the standard deviation can have any value.

C

The z score for the standard normal distribution: A) is always equal to zero. B) can never be negative. C) can be either negative or positive. D) is always equal to the mean.

C

A numerical description of the outcome of an experiment is called a A) probability function. B) descriptive statistic. C) variance. D) random variable.

D

A probability distribution showing the probability of x successes in n trials, where the probability of success does not change from trial to trial, is termed a A) uniform probability distribution. B) normal probability distribution. C) hypergeometric probability distribution. D) binomial probability distribution.

D

A statistics professor asked students in a class their ages. On the basis of this information, the professor states that the average age of all the students in the university is 24 years. This is an example of: A) descriptive statistics. B) an experiment. C) a census. D) statistical inference.

D

A weighted average of the values of a random variable, where the probability function provides weights, is known as A)the probable value. B)the variance. C)the median value. D)the expected value.

D

In a standard normal distribution, the range of values of z is from: A) -1 to 1. B) 0 to 1. C) -3.09 to 3.09. D) minus infinity to infinity.

D

The center of a normal curve is A)always equal to zero. B)cannot be negative. C)is the standard deviation. D)is the mean of the distribution.

D

The expected value of a random variable is A)the value of the random variable that occurs most frequently B)the square root of the variance C)the value of the random variable that should be observed on the next repeat of the experiment D)None of these alternatives is correct.

D

The key difference between the binomial and hypergeometric distribution is that, with the hypergeometric distribution: A) the random variable is continuous. B)the trials are independent of each other. C)the probability of success must be less than 0.5. D)the probability of success changes from trial to trial.

D

The purpose of statistical inference is to provide information about the: A) sample based upon information contained in the population. B) population based upon information contained in the population. C) mean of the sample based upon the mean of the population. D) population based upon information contained in the sample.

D

Which of the following is a characteristic of the standard normal probability distribution? A)The distribution is not symmetrical B) The standard deviation must be 0 C)The mean, median, and the mode are not equal D)The standard deviation must be 1

D

Which of the following is a required condition for a discrete probability function? A) f(x) 1 for all values of x B) ∑f(x) = 0 for all values of x C) f(x) < 0 for all values of x D) ∑f(x) = 1 for all values of x

D

Which of the following statements about cluster sampling is false?​ ​A) All elements within the randomly selected clusters form the sample B) ​Ideally, each cluster is a representative small-scale version of the entire population C) ​It provides the best results when the elements within the clusters are not alike D) it generally requires a smaller total sample size than simple random sampling

D